4,11-dichloroquinacridone pigments



ATTORNEY Aug. 18, 1970 A, P, WAGENER ET AL 4,ll-DICHLOROQUINACRIDONE PIGMENTS Filed Aug. 7, 1967 .rwmfllllll .41934 lmmn. OmZoEoZou 5R mm RE ON E d mmm n mm .5+ o: WAH

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LISNELNS United States Patent O 3,524,856 4,11-DICHLOROQUINACRIDONE PIGMENTS Anthony P. Wagener, Park Forest, and George J.Meisters,

Chicago, Ill., assignors t The Sherwin-Williams Company, Cleveland, Ohio, a corporation of Ohio Filed Aug. 7, 1967, Ser. No. 658,889 Int. Cl. C07d 37/00 U.S. Cl. 260--279 2 Claims ABSTRACT OF THE DISCLOSURE This invention comprises a new 4,1l-dichloroquinacridone pigment and the method of preparing said pigment by milling the crude compound with a solid, soluble inorganic salt and an aromatic solvent such as xylene at approximately room temperature. This new phase of the compound is distinguished by its characteristic X-ray diffraction pattern. It has an X-ray diffraction pattern having lines of' strong intensity at interplanar spacings of 6.80, 3.80, 3.52 and 3.45 angstrom units, lines of intermediate intensity at 7.08, 4.72 and 3.21 A., and weak lines at 14.40 and 3.03 A. This product also has a yellow orange color characterized by a dominant Wave length of 601.0, a light purity of 94.6%, and a reflectance, or Y value. of 18.59 at 100% pigment.

This application relates to a new 4,11-dichloroquinacridone pigment. More specifically it relates to a particular 4,11-dichloroquinacridone pigment conditioned to give a distinctive yellow-orange color and to impart a characteristic X-ray diffraction pattern. Still more specifically, it relates to a process for preparing such pigments by conditioning the crude compound by the steps of milling it with salt and xylene at approximately room temperature.

4,1l-dichloroquinacridone is described in the patent literature, namely British Pat. 896,916 (1962), Belgian Pat. 618,873 (1962), U.S. Pat. 3,085,023 (1963), and methods of preparation have also been disclosed, see U.S. Pat. 3,107,248 (1963) and U.S. Pat. 3,264,297. Two forms of this compound, namely alpha and beta, have been dened by X-ray diffraction spectra in U.S. Pat. 3,160,510 (1964). The alpha has a very yellowish orange color and the beta is a very reddish orange.

This ycompound has the structural formula:

In accordance with the practice of this invention, it has now been found that 4,1l-dichloroquinacridone of either the alpha or beta type, as well as mixtures thereof, can be converted to a new yellow shade of orange pigment having a new characteristic X-ray diffraction pattern by the steps of milling the compound with salt in the presence of an aromatic hydrocarbon or halogenated hydrocarbon, preferably xylene, at a temperature of C.-60 C., preferably about room temperature and thereafter recovering the yellow shade orange pigment product from the salt and xylene.

This new pigment has a color defined by its tristimulus values as described hereinafter. It also has a diffraction pattern characterized by lines of strong intensity of inter- ICC planar spacings at 6.80 and 3.80 A., intermediate intensity at 7.08 and 3.21 A. and a weak intensity at 14.40 A., in addition to the various lines that are found in other phases of this compound.

The figure represents graphically by three curves the X-ray diffraction patterns respectively for the new phase of this invention and for pure ,8 phase and for pure a phase of the 4,1l-dichloroquinacridone.

In preparing the new phase of this compound described herein, the crude compound, in either its alpha or beta form, or mixtures thereof, is milled with sodium chloride or other solid inorganic salt.

The inorganic salt used in the process of this invention can be of various types. Obviously it must be stable against decomposition at the temperatures used for the grinding operation and should be soluble in water or dilute acid so as to be easily removable from the dichloroquinacridone. Advantageously, it should be one not having water of hydration which will be liberated during the grinding process. Because of its inexpensiveness and availability, sodium chloride is preferred. However, other salts such as potassium chloride, ammonium chloride, ammonium sulfate, sodium sulfate, calcium carbonate, etc. can be used. These can be of commercial grade, and any absorbed moisture present can be removed by preheating the salt separate from the quinacridone prior to its use.

Also present with the salt used in the milling operation is an aromatic hydrocarbon or halogenated aromatic hydrocarbon such as xylene, toluene, benzene, methyl naphthalene, ethyl naphthalene, and their halogenated derivatives, such as chlorobenzene, dichlorobenzene, chlorotoluene, chloroxylene, dichlorotoluene, chloronaphthalene, etc. In cases where the aromatic compound is viscous or solid at room temperature appropriate raised temperatures within the specified range can be used to make the aromatic compound uid.

The amount of aromatic solvent is not critical provided there is sufficient to provide contact between the particles of the quinacridone compound and the aromatic compound. In most cases, it is generally desirable to have at least about 4 parts by weight of salt and at least 0.1016, preferably about 0.21 part by weight of xylene or other aromatic compound present per part of the 4,11-dichloroquinacridone. The amount of liquid should not be suicient to cause the pigment to coalesce.

The proportion of salt to pigment can be varied widely, ranging from 4 to 20 parts of salt per part of pigment. Very satisfactory results are obtained with about 9-10 parts of salt. Smaller amounts of salt require longer milling periods while larger amounts give no added advantage and therefore are less economical.

Various types of mills can be used for the milling or grinding operation provided they are equipped for maintaining the desired temperature. It is only necessary that in addition to maintaining the temperature, the mill provides the shearing or attrition necessary to produce the desired particle size. For example, a roller mill or an edge-runner mill or ball mill can be used. Various balls, rolls, nails, etc. are advantageously used in addition to the salt for producing the grinding effect. The grinding time will vary according to the particular type of mill and grinding material used. It is generally found desirable to mill for at least 15-20 hours depending on the efliciency of the mill. For laboratory size mills generally 24-72 hours is satisfactory, preferably about 48 hours. The milling is advantageously carried on until a particle size is obtained giving a surface area greater than 60 sq. meters per gram of material.

While room temperature is specified, the actual temperature can vary to a substantial degree. However, to

avoid the necessity for any heating or cooling means, it is generally desirable to operate at room temperature and whatever ambient temperature is generated by the grinding operation. Nevertheless, it has been found that temperatures as low as 20 C. and as high as 60 C. can be used in producing the new pigment of this invention.

The 4,1l-dichloroquinacridone used for the purpose of this invention can be prepared by heating 2,5-bis(ochloro anilino) terephthalic acid widl an alkali metal hydrogen sulfate as described in U.S. Pat. 3,107,248.

This product can also be prepared as a mixture of alpha and beta forms as described in U.S. Pat. 3,160,510 by the conversion of 2,5-bis(ochloroanilino) terephthalic acid in a manner similar to that described in U.S. Pat. 3,264,297 for the preparation of quinacridone by the use of benzoyl chloride and nitrobenzene.

It has also been found by the present inventors that beta-phase 4,11-dichloroquinacridone, or mixtures containing the alpha and beta, can be converted to the alphaphase by heating the material with a methanol solution of KOH. It has also been found that the alpha-phase, or mixtures containing the alpha-phase and beta-phase, can be converted to the beta-phase by heating the material with N-methyl pyrrolidone. It has also been found that the 4,11-dichloroquinacridone can be prepared completely in the alpha-phase by using pyridine also in the benzoyl chloride-nitrobenzene preparation referred to above.

This invention is best illustrated by the following examples. These examples are given merely for purposes 'of illustration and are not intended in any way to restrict the scope of the invention or the manner in which it can be practiced. Unless specifically provided otherwise, parts and percentages given in the examples and throughout the specification are by weight.

'EXAMPLE I A mixture of 1000 g. of 2,5-bis(ochloroanilino) terephthalic acid and 5000 c. of nitrobenzene containing 1010 g. benzoyl chloride is stirred and heated gradually over a period of two hours up to a temperature of 190 C. The mixture is then stirred at 193-195 C. for 21 hours, then cooled to 150-120 C. and filtered. The orange product is washed with 2.5 liters of nitrobenzene at 100 C., then with 3 liters of cold methanol, and dried with suction. The resultant filter cake is stirred for 1-2 hours in 3 liters of methanol and then filtered. The filtrate is again washed with 3 liters of methanol, dried with suction and then in an oven at 125 C. to constant weight. The 810 grams of orange 4,11-dichloroquinacridone represents a yield of 89% of theoretical. X-ray diffraction analysis shows that this product contains about 55% of the alpha phase and 45% of the beta phase.

Repetition of the foregoing procedure shows a yield as high as 95% can be obtained and the ratio of alpha to i beta phase as determined by X-ray analysis can vary from mostly beta to as much as 70% alpha.

EXAMPLE II A 120 gram sample of the product of Example I is refluxed and stirred 4for five hours in a solution of 300 grams of potassium hydroxide in 1200 cc. methanol. This suspension is then cooled, filtered and slurried in 3 liters of methanol for one hour. After this is again filtered, the product is washed with another liter of methanol, again sluried in 3 liters of methanol, filtered and washed with one liter of methanol. The resultant orange product is dried to constant weight at 125 C. giving 111.5 grams (93% yield) of almost pure 4,11-dichloroquinacridone in the alpha phase as identified by X-ray analysis.

When the foregoing procedure is repeated using a starting material of substantially all beta phase and various mixtures containing various ratios of alpha and beta, similar results are obtained in converting substantially completely to the alpha phase.

4 EXAMPLE In A gram sample of the product of Example I is stirred and reuxed in one liter of N-methylpyrrolidone for 8 hours. The mixture is cooled, iiltered, and the filter cake washed with 250 cc. of methanol and then dried with suction. This product is slurried in one liter of methanol for 2 hours, filtered, washed with 250 cc. of additional methanol and dried with suction, and then in an oven at C. to constant weight. The product is orange 4,1l-dichloroquinacridone in the beta phase as identified by X-ray diffraction analysis and in this case is obtained in a yield of 111.3 grams (92.5%). Upon repetition of this procedure, using various mixtures of alpha and beta phases, yields of beta phase up to 98% of theoretical are obtained.

By using the procedures of Example II and III to obtain substantially pure alpha and beta phases, various synthetic mixtures can be prepared containing various ratios of alpha and beta phases.

EXAMPLE IV In the following procedure a ball mill is used comprising a quart steel jar charged with 2500 grams of A inch diameter steel balls or a mixture of 2250 grams of such balls and 250 grams of nails No. 6D, the nails being used to help prevent `caking tendencies during milling. This jar is equipped with a lid having a suitable gasket for sealing. It is rotated by rolers whose speed is adjusted so that the rate of rotation is 106 r.p.m. In each experiment, a charge of 15 grams of 4,1l-dichloroquinacridone, 127 grams of dried sodium chloride, and 3.2 grams of xylene is used. In each case the sample and the salt together with the mill and grinding medium are stored overnight in a forced draft oven at 10D-110 C. to remove any residual moisture that may be present. The mill is then charged with the sample and the salt, and the solvent is added just prior to sealing to prevent loss of solvent during the charging period. After sealing, the jars contents are allowed to cool to room temperature prior to the start of the milling operation.

The milling is carried out for 48 hours at room temperature, the charge remaining free-flowing during the grinding operation. Upon completion of the milling, the contents of the mill are discharged, dried and separated from the steel balls by means of a coarse sieve. The product has a fine yellow-orange color and weighs grams. This product is dispersed by mixing in a Waring Blendor in 500 ml. of water for S minutes at full speed. The resultant slurry is transferred to a 300 ml. beaker and agitated by means of a sweep type agitator. To this is added a solution of 52.8 gms. of 98% sulfuric acid 479 gms. of water to yield a 5% H2804 concentration in the slurry. The resultant mixture is heated at 95-100 C. for 30 minutes after which the solids are filtered on a Buchner funnel and washed to neutrality. The resultant filter cake is dispersed in water by mixing in the Waring Blendor for three minutes in sufficient water to yield a fluid slurry. This slurry is returned to the beaker and the water volume increased to 1000 ml. It is agitated and heated at 95-l00 C. for 15 minutes after which the solids are filtered on a Buchner funnel and washed again with water. The filter cake thus obtained has a solids content of approximately 30% and is suitable for further processing as desired, i.e. flushing, preparation of dry colors, etc. The yield is 94.7% on a 100% solids basis.

Using the above procedure, seven samples of 4,11- dichloroquinacridone having 100%, 85%, 75%, 50%, 25%, 15% and 0% of the alpha phase, with the balance in each case being beta phase, are prepared by mixing the alpha and beta phases produced according to Examples II and III. In each case, the pigment conditioned according to the above procedure has a new yelloworange shade and has a diraction spectrum having interplanar spacings in angstrom units as shown in the table below which also shows the X-ray diffraction spectra for the alpha and beta phases.

The new yellow-orange color is analyzed by obtaining tristimulus data, Munsell renotations, the dominant wave length, and the percent of purity for each sample. The tristirnulus data are collected for three levels of pigmentation, namely 100%, 10% and 1% as diluted with Zn() white with the pigment in each case suspended in varnish as colorless as possible so that it contributes no color. Two parts of varnish are used per part of pigment. These measurements are made by the use of a General Electric recording spectrophotometer with a Davidson Hemmendinger tristimulus integrator and using as the reference standard a pressed BaSO4 Which is manufactured by Bausch and Lomb, Inc.

The spectrophotometer is calibrated for wavelength, reflectance level-100% line, and internal electronics before the Sample are run. From the tristimulus output of the integrator, the chromaticity coordinates x and y are calculated by summing the tristimulus values and dividing this into tristimulus X and Y.

The third variable Y is equal to tristimulus Y.

By using the chromaticity coordinates in conjunction With a set of charts which were prepared by the Color Measurement Laboratory of the Agricultral Marketing Administration, USDA, the Munsell renotations are determined. The data for these charts is based on the Final Report of the O.S.A. subcommittee on the spacing of the Munsell Colors, I. 0pt. Soc. Am. 33, 1943.

By the use of the book entitled Handbook of Colorimetry by Arthur C. Hardy; The Technology Press MIT., `Cambridge Mass., 1936, and these same chromaticity coordinates, the percent purity and the dominant wave lengths are determined.

The results obtained from such color analyses of the samples are shown below:

For the purpose of this invention the color of this product is identified by its having a dominant wave length of 601.0, a light purity of 94.6%, and a reliectance or Y value of 18.59 at EXAMPLE V The procedure of Example I is repeated except that 330 parts of pyridine are added to the benzoyl chloride nitrobenzene mixture prior to the reaction. Instead of obtaining a mixture of alpha and beta as in Example I, the product in this case is entirely the alpha phase as shown by the X-ray diffraction pattern. When this product is used in the procedure of Example IV, either by itself of in various mixtures with beta phase pro duced in Example III, similar results are obtained as in Example IV.

When the procedure of Example IV is repeated, varying the proportion of salt from 6 to 15 parts per part of sample, and varying the proportion of xylene from 0.15 to 0.25 part per part of Sample, similar results are obtained as in Example IV. Likewise, when the temperature is Varied from 20 C. to 50 C. similar results are obtained.

EXAMPLE VI The procedure of Example IV is repeated a number of times using in place of the xylene an equal weight of benzene, toluene, ethylbenzene, diethylbenzene, chlorobenzene, chlorotoluene and chloronaphthalene respectively. Satisfactory conditioning to the new phase of this invention is obtained in each case.

While certain features of this invention have been described in detail with respect to various embodiments thereof, it will, of course, be apparent that other modi- `ications may be made within the spirit and scope of this invention and it is not intended to limit the invention to the exact details shown above except insofar as they are defined in the following claims.

The invention claimed is:

1. A 4,11-dichloroquinacridone pigment having a yellow-orange color and an X-ray diffraction pattern characterized by lines of strong intensity at interplanar spacings of 6.80 and 3.80 angstrom units, lines of intermediate intensity at 7.08 and 3.21 A., and a line of weak intensity at 14.40 A.

2. A pigment of claim 1 in which the X-ray diffraction pattern has lines of strong intensity at interplanar spacings of 6.80, 3.80, 3.52 and 3.45 angstrom units, lines of intermediate intensity at 7.08, 4.72 and 3.21 angstrom units and lines of weak intensity at 14.40 and 3.03 angstrom units.

References Cited UNITED STATES PATENTS 3,007,930 11/ 1961 Manger et al 260-279 3,030,370 4/ 1962 Jackson 26o-Q79 3,148,191 9/ 1964 Jackson et al 260-279 3,201,051 8/1965 Manger et al. 241--22 3,296,008 1/ 1967 Pugin 106-288 DONALD G. DAUS, Primary Examiner U.S. C1. X.R. 106-288 

